ASPRINTF, VASPRINTF - reference manual online

Print to allocated string.

Chapter

2015-04-19

ASPRINTF(3) Linux Programmer's Manual ASPRINTF(3)NAME
asprintf, vasprintf - print to allocated string
SYNOPSIS
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <stdio.h>
int asprintf(char **strp, const char *fmt, ...);
int vasprintf(char **strp, const char *fmt, va_list ap);
DESCRIPTION
The functions asprintf() and vasprintf() are analogs of sprintf(3) and vsprintf(3), except
that they allocate a string large enough to hold the output including the terminating null
byte ('\0'), and return a pointer to it via the first argument. This pointer should be
passed to free(3) to release the allocated storage when it is no longer needed.
RETURN VALUE
When successful, these functions return the number of bytes printed, just like sprintf(3).
If memory allocation wasn't possible, or some other error occurs, these functions will
return -1, and the contents of strp are undefined.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
┌────────────────────────┬───────────────┬────────────────┐
│Interface │ Attribute │ Value │
├────────────────────────┼───────────────┼────────────────┤
│asprintf(), vasprintf() │ Thread safety │ MT-Safe locale │
└────────────────────────┴───────────────┴────────────────┘
CONFORMING TO
These functions are GNU extensions, not in C or POSIX. They are also available under
*BSD. The FreeBSD implementation sets strp to NULL on error.
SEE ALSOfree(3), malloc(3), printf(3)COLOPHON
This page is part of release 4.04 of the Linux man-pages project. A description of the
project, information about reporting bugs, and the latest version of this page, can be
found at http://www.kernel.org/doc/man-pages/.GNU 2015-04-19 ASPRINTF(3)